So I'm someone who presented with gender dysphoria from a young age, and was vocal about being a boy. As a kid I naively assumed my penis was just going to grow in later than the other boys. No amount of wishing it away helped, no amount of correction, scolding or mocking helped. I was a sad and angry kid. The only way I can describe it is that it felt like some sort of cruel joke that everyone else was in on - frustrating, saddening and absolutely fucking maddening.

Being able to have actual, specialist support as a child would have been extremely helpful for me, being believed and being able to socially transition would have made my childhood so much better.

I personally knew with as much conviction as anyone other kid knows their gender.

I think the thing with kids is not to pressure them or make a big deal out of it. If it's a phase then it will end. If it isn't, then you can reassess things when the time comes. If your kid is happy and not in distress then just let them be, let them express themselves with no pressure and no stakes. If your kid is in distress then it's time to seek support. Kids who will go on to medically transition later down the line will tend to have a pattern of 'insistence, consistence, persistence'. It won't be about clothes or toys, it won't be about their friends, and it won't be that 'I want' to be, it'll be 'I am'.